At first glance, the connection between Mars and space lettuce might seem to be a wee bit tenuous. After all, the Red Planet seems to be this shining beacon in people’s minds as THE place to go next in space. Certainly, it was the impetus for Elon Musk’s leap to fame as a builder of reusable rockets. He’s mentioned more than a few times that he wondered why we aren’t already at Mars and decided that he’d be the one to get us there. So, what does food have to do with it?

NASA, ESA, Roscosmos, India’s ISRO, and others are also aiming at Mars, and developing ways for astronauts to travel to and from other worlds (and survive nicely while doing so), so it’s not exactly a new thought.

Going to Mars (and beyond) is a standard staple of science fiction. In story after story, people blithely travel to Mars, build colonies, cities, and civilizations. In some tales, they even find indigenous life forms. So, Elon’s—and everyone else’s dream—isn’t so farfetched, in our imaginations. And, neither will be the problems we need to solve so that humans can go safely to and from other worlds of the solar system. For as much as we already know, there are a lot of other lessons we’ll be learning as we go, including bringing our habitat and food (and space lettuce) with us.

Danger, Danger

Reality, however, has a different take on things. The advent of space travel taught a visceral lesson about moving beyond Earth: it’s dangerous. We evolved to live and propagate on Earth. Going elsewhere means that we have to take our environment with us. Hence the pressurized space stations, spacecraft, suits, and other needs. And, as astronauts have learned with their own bodies, living and working in space presents hidden dangers to their health. Bones soften. Eyes change. Organs change. Even the space traveler’s mental condition is subject to change. Lengthy missions in space will challenge even the hardiest among us. And, we’ve never had the experience of living for long periods on other worlds.

Gardening (and Space Lettuce) May Hold the Key

As much as possible, anyone who lives and works in space needs to take precautions to preserve their health. Future astronauts may well adapt to space through a combo of diet and exercise, much as those of us here on Earth try to preserve our health here in the gravity well. This works especially well for our bones. They evolved to be constantly balanced between the processes of growth and resorption. They can repair themselves when injured and grow as our bodies grow. However, take our bones into space, and things aren’t the same. Living in a low- or microgravity environment causes bones to lose mass in the process of resorption. This is why you see images of astronauts exercising like mad while on orbit. If they don’t, their bones soften.

Now, on short missions, this poses a problem that gets solved when the astronaut returns to Earth. But, what happens if the astronaut is leaving Earth, going on a lengthy trip to Mars, and then spending time on the Red Planet? Yes, they can exercise like crazy, but the changes are going to be very hard to reverse if and when they return to Earth. There has to be another solution, like growing some kind of food that will help maintain bones and other body systems.

Salad in Space

It turns out biologists and doctors have been researching other ways to “fix” the problem. One of them turns out to be something edible: space lettuce. This is a form of lettuce that its developer calls “transgenic”. It was developed by Kevin Yates, a graduate student at the University of California Davis department of chemical engineering. He’s created this lettuce that utilizes a fusion protein that combines a parathyroid hormone with a human antibody protein. Parathyroid hormones can be used to treat bone loss here on Earth. So, this new space lettuce would not only be a source of a drug they could use to ward off bone loss while in transit and on Mars, but it would give them a fresh, renewable source of food along the way.

Long space flights like a trip to Mars are always going to pose challenges since the missions will need to bring along stocks of consumables such as medicines. Astronauts have been growing food on space stations for years, so space gardening technology is fairly robust. Being able to grow them along the way is a step forward to a renewable source of consumables in space.

There’s been a lot of talk lately about asteroid mining and resources, particularly among the space-exploration investment folks. The topic is something you hear a lot about from players in the New Space arena. But, how likely is it that we’ll find nearby asteroids to explore and exploit? If you’re an astronomer, how much chance will you get to study asteroids without having to send probes beyond Earth’s orbit?

Those questions and many others are behind the search for nearby ones in stable orbits. They’re called Earth Trojan asteroids. They should lie at the same distance from the Sun as Earth, at orbital positions called LaGrange points. Most of the other planets have their own Trojan asteroids, too, so it shouldn’t be a surprise to find them near our planet.

As it turns out, today we know of two of Earth trojan asteroids. Astronomers confirmed the first one in 2010. It’s called 2010 TK7. and measures about a third of a kilometer across. The second one was just confirmed and announced in the journal Nature Communications on February 1, 2022. It’s called 2020 XL5. It’s bigger, about a kilometer in diameter. It likely was pushed into its current orbit by a close encounter with the planet Venus in the 1500s. It doesn’t pose a threat to us and will likely remain in that orbit for a few thousand years.

There are probably more of these near-Earth and “safe” asteroids nearby, but we haven’t found them yet. Still, they do offer a good place to study for planetary scientists. For the corporate types who see space as a place to make their fortunes, these could be places to mine for resources.

Trojan Asteroids Offer Riches

Earth Trojans have the potential to give us a lot of information about conditions in the solar system at the time Earth formed. That’s because their compositions might be pretty similar to the planetesimals that formed our planet. They could have been orbiting in the same part of the inner solar system as Earth and the Moon. That means their orbital histories may give us insight into the dynamical motions of the time.

Since they’re relatively close to us and in the same orbit as Earth, they could also make good targets for future space missions. The energy requirements are much lower than heading out to Mars and beyond. Finally, in an age where people are talking about mining asteroids, these might be good places to look for scarce minerals.

Finding Earth Trojan Asteroids

These little asteroids are tough to spot. Since they orbit at Earth’s L4 or L5 points, they generally are be seen close to the Sun from Earth. That gives observers a pretty small window of opportunity to observe them. In addition, observing conditions aren’t great at the time when they can be seen, generally just before sunrise. People run the risk of saturating their telescope detectors with sunlight. In addition, they are looking through a thicker part of the atmosphere at the horizon. It’s a risky business to aim a large, expensive telescope during an asteroid search, but there are rewards for those who do.

The Spanish team that found this second Earth Trojan asteroid used the 4.3-meter Lowell discovery telescope in Arizona and the 4.1-meter SOAR telescope in Chile. This discovery was the result, and it’s encouraging news. Certainly, there are others out there; it’s just going to take time and patience to find them out at Earth’s LaGrange points.